1. Field of the Invention
The present invention relates to a plate for use as part of an external fixation device, and more particularly to a unique hole pattern within the plate.
2. General Background and Description of the Prior Art
Traditional circular ring external fixation devices consist of Ilizarov-type devices that are based on a circumferential external fixator system disclosed by G. A. Ilizarov during the early 1950's. The Ilizarov system includes at least two rings or “halos” that encircle a patient's body member (e.g., a patient's leg), connecting rods extending between the two rings, transfixion pins that extend through the patient's boney structure, and connectors for connecting the transfixion pins to the rings. Use of the Ilizarov system to deal with angulation, translation and rotation is disclosed in “Basic Ilizarov Techniques,” Techniques in Orthopaedics®, Vol. 5, Nov. 4, December 1990, pages 55-59.
The Ilizarov system provides an external fixation frame that allows for gradual correction along and about six axes; however such frames require many parts and are relatively complicated to build and use in a clinical situation. In addition, often orthopedic external fixators such as Ilizarov frames must be modified after their initial application. Such modification may be necessary to convert from one correctional axis to another. Alternatively, such modifications may allow conversion from an initial adjustment type of frame to a weight bearing type frame, since some of the correctional configurations are not stable enough for weight bearing.
The rings used in the Ilizarov devices include a plurality of spaced apertures or holes that allow for the attachment of various accessories to the device. The pattern of Ilizarov ring holes is primarily determined as a function of the diameter of the ring. Conventional wisdom teaches that for any given diameter, the ring should include the maximum number of equally spaced arcuately positioned holes. Those skilled in the art believe that such hole positioning provides the surgeon with the greatest degree of flexibility in constructing the often times complicated and elaborate Ilizarov frame configuration. The Ilizarov ring holes, although equally spaced about a circle, are positioned such that the location of any given hole relative to another hole on additional rings attached thereto, is completely irrelevant.
Applicants have recently developed a new external fixation device known as the Taylor Spatial Frame™ external fixator. This device is described and claimed in the allowed U.S. patent application Ser. No. 08/782,731 entitled “Orthopaedic Fixation Device.” In addition, applicants have developed a unique method of using the Taylor Spatial Frame™ fixator that is the subject of allowed U.S. patent application Ser. No. 08/726,713 entitled “Method of Using An Orthopaedic Fixation Device.” Both of these patent applications are incorporated herein by reference. As disclosed in these prior patents, the Taylor Spatial Frame™ fixator, in its preferred embodiment, consists of two ring plates interconnected by six adjustable length struts. This device can be configured to correct virtually an infinite number of deformities, each of which would have otherwise required the construction of a specific custom Ilizarov frame.
As with the prior art Ilizarov fixator, the Taylor Spatial Frame™ fixator plates include a plurality of spaced apertures or holes therethrough for attaching accessories to the device. In addition, the plates include plurality of cavities or holes for attachment of the struts to the rings. Applicants have now developed a unique hole placement scheme for the Taylor Spatial FRAME™ fixator rings. This unique hole placement scheme takes advantage of the unique nature of the Taylor Spatial Frame™ fixator and the unique method of using the same, and provides substantial advantages over the unsystematically placed hole patterns utilized in Ilizarov rings.